package com.practice.generic;

import java.util.ArrayList;
import java.util.List;

public class Main {

	public static void main(String[] args) {
		
		List <? extends Number> producerNumberList = new ArrayList<Number>();
		List <? extends Number> producerIntegerList = new ArrayList<Integer>();
		List <? extends Number> producerDoubleList = new ArrayList<Double>();
		
		producerNumberList.add(null);
		Number number = producerNumberList.get(0);
		
		List<? super Integer> customerIntegerList = new ArrayList<Integer>();
		List<? super Integer> customerNumberList = new ArrayList<Number>();
		List<? super Integer> customerComparableList = new ArrayList<Comparable>();
		
		customerIntegerList.add(new Integer(0));
		Object object = customerIntegerList.get(0);
	}

}
